A. Technical Field
The present invention relates to a production process for an ethylene oxide copolymer. More particularly, the present invention relates to a production process for an ethylene oxide copolymer as obtained by carrying out ring-opening polymerization of monomers including a substituted oxirane compound.
B. Background Art
Ethylene oxide and a group of substituted oxirane compounds have hitherto been used as raw monomers of various polymer materials in view of their rich reactivity and high industrial usability. Then, ethylene oxide copolymers as obtained by carrying out polymerization of the above raw monomers are used as polymer materials in very wide-ranging uses, such as: polyurethane resins (e.g. adhesives, paints, sealing agents, elastomers, and floor-polishing agents); and besides hard, soft, or half-hard polyurethane resins; and surfactants, sanitary products, deinking agents, lubricating oils, engine-starting oils, and polyelectrolytes.
Usually, polymer materials have different molecular weights that are desired each in various uses. Therefore, in order to display such as their excellent properties, it is important how the polymer materials having molecular weights corresponding to the various uses can be prepared in a state of little scatter. Accordingly, also when the ethylene oxide copolymers are used, it is necessary to control the molecular weights of the above copolymers depending upon each use, and such as production processes and preparation techniques for the above copolymers are very important.
However, the substituted oxirane compounds as the raw monomers of the ethylene oxide copolymers easily accompany a chain transfer reaction during the polymerization. As a result, there is a problem such that the lowering of the molecular weights of the above copolymers is easily caused, and therefore it has been very difficult to obtain ethylene oxide copolymers having desirable molecular weights with good reproducibility.